Trackpad input devices use tactile sensors to map the motion and position of a user's finger or other object to a relative position on a screen. The trackpad input device was introduced as an alternative and replacement to trackballs, which rely on sensors to track the rotation of a ball within a socket, and pointing sticks, which operate by sensing applied force using a pair of resistive strain gauges. Trackpad input devices are commonly found on laptop computers but can be used as a substitute for any number of pointing input devices.
Trackpad input devices make use of capacitive sensing, conductive sensing, or other technologies to track the position of an object. A user can interact with a trackpad input device by sliding their finger along the surface of a trackpad input device to control a cursor on a display. Additionally, some trackpad input devices include the ability to interpret tapping of the trackpad input device to indicate a “click” or selection of an object on a display. Moreover, some trackpad input devices include proximity or depth sensors capable of sensing movement within a volume or sensing region.
The settings associated with a trackpad input device or the associated device driver software may allow a user to adjust the sensitivity to touch of the trackpad input device. For example, with a high trackpad input device speed setting, a one-inch slide of a finger on the trackpad input device might result in a cursor moving across the entire screen of a display, while a low trackpad input device speed setting might produce a movement across one quarter of the screen in response to the same one-inch slide. Similarly, the sensitivity to tapping may be configurable. A trackpad input device with high touch sensitivity setting might notice a light tap on the touch screen, while a trackpad input device with a low touch sensitivity setting might not be able to detect the same light tap.